The present invention relates generally to display devices and particularly to a system and method that provides adaptive color and contrast for a display device.
A display device renders input data as a two-dimensional image in color or grayscale. The input data may be graphical in nature. An example of such a device is a PC display monitor. The input data may be a video signal. An example of such a device is a TV or video monitor. The input data may be a combination of graphics and embedded video. An example of such a device is a PC display monitor displaying graphics with one or applications displaying video in a window, or a PC/TV display device with two or more input ports displaying graphics or fill-screen video or a combination of graphics and video, e.g. Picture-in-Picture.
A viewer typically manually controls the color and contrast of a display device. The issue with manual control is that it does not result in optimal display quality for all possible input data. For example, setting the contrast control to increase the contrast of a washed out image will result in over-contrasty images for a normal image. Decreasing the color saturation setting for a highly saturated image would be optimal, but if the input changes to a de-saturated image, this setting would now be sub-optimal. It is not feasible or convenient for a viewer to continuously change display settings to adapt to the nature of the input image, particularly when the input is a video sequence.
Another problem with manual control of contrast and color is that it is not sensitive to the nature of the input data. Manual contrast control applies a multiplicative factor to the input luma component. This is shown graphically in FIG. 1. Due to the finite dynamic range of luma values, increasing the contrast of a dark image in order to be able to see the shadow details results in loss of information in the bright highlights. The multiplicative nature of this control also implies that there is no possibility of increasing the contrast of a predominantly bright image.
Accordingly, what is needed is a system and method to address the above-identified problems. The present invention addresses such a need.
A method and apparatus that allows a display device to adaptively and automatically control display contrast and color is disclosed. The method and system in accordance with the present invention can be described by the following sequential process:
1. Separating an input image data value into its luma and chroma components.
2. Collecting the luma distribution data over the entire image or a specified window.
3. Analyzing the luma distribution.
4. Generating an appropriate contrast control response that modifies the input luma component to generate an output luma component, on a pixel by pixel basis.
5. Analyzing the input luma component and the output luma component, and an input chroma component, to generate an appropriate modification for the chroma component, on a pixel by pixel basis.